The present seal structure yields a very important benefit over prior seal systems, in addition to providing most of the benefits of these seals. Previous seals, an example of which is shown in FIG. 1, have a tendency to cut or wear a circular groove into the associated rotary shaft. Theses grooves are primarily caused by the frictional contact between the faceplate wiper ring 189 and the shaft 121, as the shaft is rotated during normal operation of the machine. It is undesirable to have the wiper ring cutting a groove into the rotary shaft during operation because these grooves weaken the shaft and can eventually lead to cracking of the spindle. It is equally undesirable to remove the wiper ring from the seal faceplate, because the wiper ring provides an initial barrier against environmental contaminants. Therefore, the present invention alleviates the tendency of the wiper ring to cut or groove the rotary shaft, without compromising the overall seal quality.
These and further objects of the apparatus taught in accordance with this specification, the claims, and the appended drawing figures are set forth below.